BUG_ON() will be triggered when writing files concurrently,
because the same page is writtenback multiple times.
1597 void folio_end_writeback(struct folio *folio)
1598 {
......
1618 if (!__folio_end_writeback(folio))
1619 BUG();
......
1625 }
kernel BUG at mm/filemap.c:1619!
Call Trace:
<TASK>
f2fs_write_end_io+0x1a0/0x370
blk_update_request+0x6c/0x410
blk_mq_end_request+0x15/0x130
blk_complete_reqs+0x3c/0x50
__do_softirq+0xb8/0x29b
? sort_range+0x20/0x20
run_ksoftirqd+0x19/0x20
smpboot_thread_fn+0x10b/0x1d0
kthread+0xde/0x110
? kthread_complete_and_exit+0x20/0x20
ret_from_fork+0x22/0x30
</TASK>
Below is the concurrency scenario:
[Process A] [Process B] [Process C]
f2fs_write_raw_pages()
- redirty_page_for_writepage()
- unlock page()
f2fs_do_write_data_page()
- lock_page()
- clear_page_dirty_for_io()
- set_page_writeback() [1st writeback]
.....
- unlock page()
generic_perform_write()
- f2fs_write_begin()
- wait_for_stable_page()
- f2fs_write_end()
- set_page_dirty()
- lock_page()
- f2fs_do_write_data_page()
- set_page_writeback() [2st writeback]
This problem was introduced by the previous commit 7377e853967b ("f2fs:
compress: fix potential deadlock of compress file"). All pagelocks were
released in f2fs_write_raw_pages(), but whether the page was
in the writeback state was ignored in the subsequent writing process.
Let's fix it by waiting for the page to writeback before writing.
Fixes: 4c8ff7095bef ("f2fs: support data compression")
Fixes: 7377e853967b ("f2fs: compress: fix potential deadlock of compress file")
Signed-off-by: Qi Han <[email protected]>
Signed-off-by: Yangtao Li <[email protected]>
---
fs/f2fs/compress.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index 93fec1d37899..904af359fa8e 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -1456,6 +1456,14 @@ static int f2fs_write_raw_pages(struct compress_ctx *cc,
if (!PageDirty(cc->rpages[i]))
goto continue_unlock;
+ if (PageWriteback(cc->rpages[i])) {
+ if (wbc->sync_mode != WB_SYNC_NONE)
+ f2fs_wait_on_page_writeback(cc->rpages[i],
+ DATA, true, true);
+ else
+ goto continue_unlock;
+ }
+
if (!clear_page_dirty_for_io(cc->rpages[i]))
goto continue_unlock;
--
2.35.1
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